The present invention generally relates to a first lane detection sensor for detecting opposite lane markers of a road, in which the lane markers are preliminarily obtained as a plurality of spline curves and points in Hough space are obtained by using coefficients of the spline curves corresponding to the lane markers so as to obtain the lane markers at high speed, a second lane detection sensor for detecting opposite lane markers of a road, in which the lane markers are detected by using a low-resolution image from a high-definition image so as to detect curves of the lane markers smoothly, a third lane detection sensor for detecting opposite lane markers of a road, in which shapes of curves of the lane markers ahead of a running motor vehicle are forecast by using a map data base, an arithmetic unit for approximating a radius of curvature of a road from an angle formed between two tangents for the lane markers, a first navigation system for storing data of a road on which a motor vehicle has run and a second navigation system for guiding a driver from a lane on which his motor vehicle is running and position of the lane.
A conventional lane detection sensor is disclosed in, for example, Japanese Patent Laid-Open Publication No. 5-151341 (1993) as shown in FIG. 16. The known lane detection sensor includes an image input means 100 for shooting an image of a road ahead of a running motor vehicle, a preparation means 101 which receives a signal from the image input means 100 so as to extract an edge point, a line adaptation means 102 which sets a window in the vicinity of a linear equation obtained at the time of a previous arithmetic operation and measures coordinates of a plurality of edge points in the set window so as to obtain a plurality of linear equations through linear approximation, a line and vanishing point determining means 104 which estimates x- and y-coordinates of a vanishing point and amounts corresponding to slopes of straight lines passing through the vanishing point on the basis of the obtained linear equations so as to minimize a sum of square of errors among the linear equations and sets these estimated values to a result of this time, an edge point tracing means 103 which extracts, on the basis of a result of the preparation means 101 and a detection result of the linear adaptation means 102, an edge point corresponding to a lane marker, a curve adaptation means 105 which applies a curved equation to the extracted edge point and a smoothing means 106 for smoothing a result of the curve adaptation means 105.
In this known lane detection sensor, application of the curved equation is performed by method of least squares and therefore, is readily affected by noises. As a result, it is impossible to detect the lane makers accurately.
Meanwhile, a known detection apparatus for detecting a radius of curvature of a road is disclosed in, for example, Japanese Patent laid-Open Publication No. 2-115905 (1990) as shown in FIG. 17. The known detection apparatus includes an imaging means 107 for shooting an image of an external environment, a detection means 108 for detecting from the image a target along a route of a running motor vehicle and relative positional relation between the target and the running motor vehicle, a track generating means 109 for generating a track regulated by a predetermined function based on the relative positional relation and a control means 110 for controlling running of the motor vehicle in accordance with the generated track.
In this prior art detection apparatus, since the radius of curvature of the road is determined on the basis of the distant landmark, errors of the radius of curvature of the road are large and thus, it is impossible to obtain the radius of curvature of the road accurately.
Furthermore, conventionally, a navigation system loaded on a motor vehicle can receive only predetermined map data but cannot receive data available during running of the motor vehicle. In addition, in the conventional navigation system, it has been difficult to guide the motor vehicle accurately when the motor vehicle is running across a plurality of lanes.